This study is a prospective, single-center, randomized, double-blind, double-dummy, crossover trial of Depakote ER vs. Seroquel for agitated behaviors among veterans with dementia. After consent is obtained and after a washout period of one week or five half-lives after taper (if necessary), 20 eligible patients will be randomized to received one of two treatments. The first is DEPAKOTE ER, initiated at 250 mg daily. The other treatment will be Seroquel, starting at 25 mg BID. Both treatments will be co-administered with a placebo that matches the other drug (to preserve blinding). Using serial examinations and blinded laboratory reporting, doses will be adjusted to clinical response or to achieve a serum valproate level of at least 50 mcg/mL. After a treatment period of six weeks, patients will be crossed over to the other treatment without washout (doses will be adjusted concurrently) for a second six-week treatment period. The Cohen-Mansfield Agitation Inventory (CMAI) will be the primary outcome measure. Secondary measures include the Behavior Pathology in Alzheimer's Disease Rating Scale (BEHAVE-AD); Clinical Global Impression Scale - Severity; Clinical Global Impression Scale - Improvement; Barnes Akathisia Scale (BAS); and the Abnormal Involuntary Movements Scale (AIMS). Outcome measures will be performed at the end of each six-week treatment period to avoid carryover effects.